In imaging apparatuses, for example, digital cameras, when a deep subject is shot by an autofocus, there is possibility that a so-called focusing error (focusing misalignment) which focuses on a position where a photographer does not intend as a result of a limitation of performance of an algorithm or hardware. In such a case, a method of using a focus-bracket shooting as a countermeasure of deviation or variation in focusing is known (for reference, see Japanese Patent Application Publication No. 7-318785).
However, in the focus-bracket shooting, it is difficult to avoid a great focusing misalignment because it is usual to take shootings of about three times by moving slightly a focal position forwardly and backwardly. There may be a case that a photographer wants to select a best shot by viewing and comparing shot images after a plurality of shootings are taken by changing a focal position positively without deciding whether focusing on what subject fits, before shooting.
From these two backgrounds, it is considered that a convenient focus-bracket shooting capable of moving throughout a focusing range broader than that of the existing focus-bracket shooting and having focusing position-information of a subject is potentially demanded in a market. There is possibility that increasing immoderately the number of the focus-bracket shootings results in a cost up of instruments with increment in buffer memory capacities, or reduction in usability due to increment in times required for shooting and processing a record, if a compact type-digital camera has shooting numbers exceeding 40, in light of a recent background that the compact type-digital camera has recording pixels of ten million.
Therefore, to execute a focus-bracket shooting, the inventors of the present application have proposed an imaging apparatus configured to divide a picture plane into small sections, perform a hill-climbing scan by a detection frame unit of each small section, decide an entire focal position by comparing a distribution of focal positions in each small section and predetermined threshold values, and decide the number of shootings by the focus-bracket shooting, as disclosed in Japanese Patent Application No. 2008-238757.
However, in a hill-climbing scan used in the existing focus bracket shooting, there is generated a variation between a reproduced image and a display of focusing-area frames because data determining a focusing area and shot images are separate each other. When taking a shooting with a handheld camera, there is an influence that it is not possible to continue to hold the camera so that a field angle of the camera does not deviate during a time from the beginning of the hill-climbing scan to the end of shooting. If a focal distance of a shooting is close to a telescopic end, the influence cannot be ignored, and there is a problem of generating a great variation between a shot image and a reproduced image.